An ultrasonic machining tool is known from Swiss patent No. 665,784, where the tool or the sonotrode is attached by means of a differential screw. The device has an axial borehole, to which a wrench is permanently installed in order to tighten and loosen the differential screw. The wrench can be moved axially relative to the device and is prestressed by means of a spring into its retracted position, where it is disengaged with the differential screw. To rotate the screw, the wrench is engaged by a lifting magnet and subsequently rotated. This kind of manual connection gives satisfactory results for ultrasonic machining, but does not lend itself to automated control.